As mentioned maybe in free air but on the track no engine is comming beyond the 50,000rpm. The only one who did was the Orion CRF Wasp, it needed a light gearing to come alive reaching the same speeds as others on a heavy gearing. Regarding the designer of that engine it has runned 55.000 rpm on a testbench.

Yeah the Nikasil coated Orion Wasp engines were very special! But they were very hard to tune! But I've never had another engine in .12 size compare to one of those.

As mentioned maybe in free air but on the track no engine is comming beyond the 50,000rpm. The only one who did was the Orion CRF Wasp, it needed a light gearing to come alive reaching the same speeds as others on a heavy gearing. Regarding the designer of that engine it has runned 55.000 rpm on a testbench.

Acrually, that engine has done 62000rpm is a car tested with optic sensor.